The present invention relates generally to library apparatuses storing and handling a plurality of recording media, such as DVDs (Digital Versatile Disks) and CDs (Compact Disks), where a designated recording medium is positioned in a plurality of predetermined positions for transportation, via a carrying holder (carrier) unit, between a storage unit and a medium drive unit, and more particularly to an improved medium-positioning technique that permits accurate positioning of the designated recording medium in the predetermined positions in a highly simplified manner.
Conventionally-known recording media library apparatuses (hereinafter also referred to as xe2x80x9clibrary apparatusesxe2x80x9d) are designed so that a recording medium, such as an optical disk, contained in a predetermined case or cartridge is transported automatically by a computer-controlled carrying holder unit between a storage unit and a medium drive unit and the thus-transported medium is driven via the drive unit for data read or write. Namely, such library apparatuses generally comprise the carrying holder unit automatically-controlled for retaining and transporting a designated recording medium, usually in horizontal and vertical directions, the storage unit for storing a multiplicity of the recording media in respective storage cells (or on respective storage racks), and the medium drive unit that reads or writes data on the recording medium. The carrying holder unit includes a picker mechanism which has a locking member, commonly called a locking claw or picker, engageable with the recording medium. For transfer of the designated recording medium between the holder unit and the storage unit or the drive unit, the picker mechanism drives the locking member or picker, with the recording medium locked thereby, to move the recording medium within a predetermined travel range. When, for example, the recording medium stored in a particular one of the storage cells is to be driven by the medium drive unit for data read or write, the carrying holder unit is first moved to the particular storage cell to pull the recording medium out of the storage cell into a predetermined place of the holder unit using the picker, after which the holder unit, retaining the recording medium, is moved over to the medium drive unit and sends the thus-transported medium into the drive unit using again the picker. Thus, by means of the picker, each designated recording medium can be transferred or passed between the storage cell and the carrying holder unit or between the carrying holder unit and the medium drive unit; hereinafter, such a transfer of the recording medium using the picker will be called a xe2x80x9cfeed transferxe2x80x9d.
More and more DVDs (Digital Versatile Disks) have been used as high-density digital recording media in recent years. However, so far, there has been proposed no library apparatus capable of efficiently handling the DVD recording media.
For example, when the power supply to the conventional library apparatus is turned OFF during the course of a feed transfer of a particular recording medium, the recording medium is undesirably halted and left xe2x80x9cpendingxe2x80x9d unsettled halfway through the intended transfer, which would lead to significant inconveniences on and after resumption of the power. Thus, in turning ON the power (at power-ON), it was absolutely necessary to properly ascertain whether or not any recording medium is left pending or unsettled halfway through a feed transfer. To this end, it has been customary for a human operator to visually ascertain the current conditions of the library apparatus and, in case any recording medium is found to be halted halfway through a feed transfer, manually move the picker out of the locking engagement with the recording medium to thereby remove the medium from the library apparatus or manually move the medium for settlement in a predetermined position.
Further, in the case where the designated recording medium is transferred through a reciprocating movement of the picker within the predetermined travel range, there would arise a need to accurately detect a current position of the picker for precise control of its movement. However, the existing general-purpose picker position detectors are relatively expensive and can never be said to be simple in structure. While the incremental pulse encoder is known today as a relatively inexpensive general-purpose detector, it is not capable of detecting absolute positions, so that if the picker is halted in a position halfway through the transfer due to power shutoff, there would be encountered the problem that the incremental pulse encoder is unable to properly perform its position detecting operation after resumption of the power.
It is therefore an object of the present invention to provide a recording media library apparatus which can properly detect a current position of a recording medium with a simple structure and thereby appropriately control transfer of the recording medium.
It is another object of the present invention to provide a recording media library apparatus which, when any recording medium is found, upon power-ON, pending halfway through a feed transfer, can automatically perform control to move and settle the pending recording medium in a predetermined position.
It is still another object of the present invention to provide a recording media library apparatus which can detect any necessary position of a picker in absolute form by means of a position detector that is inexpensive and simple in structure.
In order to accomplish the above-mentioned object, the present invention provides a recording media library apparatus which comprises: a storage section that stores a recording medium; a carrier unit that carries a recording medium; a drive unit that reads or writes data on a recording medium; a medium transfer mechanism that includes a locking member engageable with a recording medium and moves the recording medium within a predetermined travel range with the recording medium engaged by the locking member, to thereby allow the recording medium to be transferred between the carrier unit and the storage section or the drive unit; a picker position detector unit that detects a current position of the locking member to determine which of a plurality of predetermined points within the travel range the current position of the locking member corresponds to; and a controller unit that performs control to determine a current position of the recording medium within the travel range on the basis of an output of the picker position detector unit.
The recording media library apparatus of the present invention is characterized primarily in that control is performed for determining a current position of a recording medium indirectly on the basis of an output from the picker position detector unit that detects a current position of the locking member (known as a locking claw or picker in the art). This arrangement eliminates a need to provide a detector dedicated to directly detecting a current position of the recording medium within the predetermined travel range and can substantially simplify the structure of the library apparatus accordingly. As a result, the current position of the recording medium can be accurately detected with a simplified structure, which thus permits appropriate control of the library apparatus, such as medium transfer control for initializing a recording medium to a predetermined rest position at power-ON, control for properly positioning a recording medium for transportation between the carrier unit and the storage section or the drive unit.
In a preferred implementation of the present invention, the controller unit controls transfer of the recording medium by the medium transfer mechanism on the basis of the output of the picker position detector unit, to allow the recording medium to be properly placed or settled in a predetermined rest position. The predetermined rest position in the present invention is where the recording medium is completely stored in any one of the carrier unit, storage section and drive unit, rather than being pending or unsettled halfway between the carrier unit and the storage section or the drive unit. Thus, in cases where the present invention is applied to the medium transfer control for initialization of a recording medium position at power-ON, the controller unit, at power-ON (i.e., turning-ON of the power to the apparatus), determines on the basis of the output from the picker position detector unit whether or not the recording medium is properly placed in the predetermined rest position. If the recording medium is unsettled or pending halfway through an intended transfer, i.e., if the recording medium is not in the predetermined rest position, the controller unit can automatically adjust the position of the recording medium for proper settlement in the predetermined rest position. Consequently, even in the case where, upon power-ON, any recording medium is found unsettled or pending halfway through an intended transfer, the recording medium can be automatically moved, under the control of the controller unit, to the predetermined rest position, so as not to prevent the library apparatus from starting its operation properly. This allows the library apparatus to efficiently start working, without a need for any prior manual operation by a human operator as discussed above.
For more efficient operation, the recording media library apparatus may include a plurality of storage sections disposed to the opposite sides of the carrier unit with the drive unit disposed to either one of the two sides. In such a case, the recording media can be fed horizontally to and from the carrier unit in the opposite directions; that is, leftward and rightward feed transfers of recording media are permitted. Thus, it would be more convenient if each recording medium is constructed to be engaged by the locking member selectively at one of different portions depending on whether the intended feed transfer is leftward or rightward. In this case, however, the positional relationship between the locking member and the recording medium has to differ between the leftward feed and the rightward feed. Taking this into account, it is preferable that the library apparatus according to the present invention further comprise a detecting section for detecting any recording medium pending or unsettled halfway between the carrier unit and the storage section or the drive unit, and that the controller unit control the transfer of the recording medium by the medium transfer mechanism on the basis of respective outputs of the detecting section and the above-mentioned picker position detector unit to allow the recording medium to be placed or settled properly in the predetermined rest position. Namely, because the detecting section allows the leftward and rightward feed transfers to be distinguished from each other, the recording medium can be properly controlled to be settled in an appropriate rest position.
In a preferred implementation, the above-mentioned picker position detector unit is provided in association with a drive shaft for the locking member of the medium transfer mechanism, and the picker position detector unit includes at least one transmission shaft to which rotational force of the drive shaft is transmitted at a predetermined transmission ratio, and a plurality of sensor sections provided in corresponding relation to at least the drive shaft and the transmission shaft, each of the sensor sections generating a rotational position detection signal corresponding to at least one predetermined rotational angle of a corresponding one of the shafts while the corresponding shaft is rotating. The picker position detector unit detects the plurality of predetermined points in absolute form on the basis of a combination of generation patterns of the rotational position detection signals generated by the sensor sections. In this arrangement, there occurs a predetermined difference between the rotating angles of the drive and transmission shafts, so that a combination of the rotating angle patterns of the individual shafts can correspond to a current absolute position of the locking member. As a consequence, each of the predetermined points defined for the locking member can be identified, in absolute values or form, on the basis of a combination of the generation patterns of the rotational position detection signals, corresponding to the individual shafts, output from the sensor sections. Because the sensor sections each may be of a simple structure which can only generate a rotational position detection signal responsive to at least one predetermined rotational angle of the corresponding shaft, they can be extremely simpler in structure and inexpensive as compared to the existing general-purpose absolute encoders. Therefore, the present invention can provide a more sophisticated recording media library apparatus which is capable of detecting any necessary positions with such a picker position detector unit that is very inexpensive and simple in structure.
Further, in a preferred implementation, the controller unit performs control for placing or settling any xe2x80x9cpendingxe2x80x9d recording medium in the predetermined rest position upon power-ON, and also includes an initialization control that, after the recording medium is thus settled in the predetermined rest position, initializes the medium transfer mechanism in such a way that the locking member disengages from or release the recording medium and is then positioned at a predetermined reference point. Namely, at power-ON, the controller unit automatically ascertains the current position of the recording medium left pending after the power-OFF or power shutoff, settles the medium in any one of the storage section, carrier unit and drive unit and then positions the locking member at the predetermined reference point. Thus, even when the power was turned OFF during the course of a feed transfer of a recording medium with the medium left engaged by the locking member, the initialization control, upon following power-ON of the library apparatus, can automatically initialize both the recording medium and the locking member to respective appropriate positions, with the result that the library apparatus can work with increased efficiently.
Every time the locking member is found left in engagement with a recording medium with at least part of the medium received in the carrier unit when the operation is to be performed, upon power-ON, for positioning the locking member at the predetermined reference point, the recording medium is first transferred into a predetermined place of the carrier unit and the locking member is retracted out of the engagement with the medium, after which the control is performed for moving the locking member to the predetermined reference point. To this end, the recording media library apparatus may further comprise a detecting section that detects any recording medium pending or unsettled between the carrier unit and storage section or drive unit. The controller unit may control the transfer of the recording medium by the medium transfer mechanism on the basis of respective outputs of the detecting section and the picker position detector unit to allow the recording medium to be properly settled in the predetermined rest position. In this case, it is preferable that the predetermined rest position be where the recording medium is completely stored in any one of the carrier unit, storage section and drive unit. Because, in the case where there is any recording medium pending or unsettled between the carrier unit and storage section or drive unit, it is very likely that another recording medium is received in the storage section or drive, although no other recording medium, than the pending recording medium, is present in the carrier unit. Therefore, if the pending recording medium is fed to the storage section or drive unit that may contain another recording medium, there is a chance of these media colliding against each other. To avoid such an inconvenience, whenever at least part of the medium is found received in the carrier unit at turning-ON of the power to the library apparatus, the pending recording medium is first fed to the carrier unit so that it is temporarily positioned completely within the carrier unit.
The present invention also provides a recording media library apparatus which comprises: a storage section that stores a recording medium; a carrier unit that carries a recording medium; a drive unit that reads or writes data on a recording medium; a medium transfer mechanism that transfers the recording medium between the carrier unit and the storage section or the drive unit; a detecting section that detects any recording medium pending halfway between the carrier unit and the storage section or the drive unit; and a controller unit that, when the detecting section detects the recording medium at turning-ON of the power to the recording media library apparatus, controls the medium transfer mechanism to transfer the recording medium into a predetermined place of the carrier unit.
When the power is shut off during the course of a feed transfer (handling) of a recording medium by the carrier unit, the medium would be halted and left pending halfway between the carrier unit and the storage section or the drive unit as mentioned earlier. If, at following turning-ON or restoration of the power, the carrier unit is moved in the vertical direction or the locking member is returned to a predetermined reference point while still engaging the pending recording medium without executing any appropriate positional initialization of the medium, the medium projecting from the carrier unit would collide against another mechanism in the library apparatus or would be displaced by the locking member returning to the reference point to collide against another recording medium stored in the storage section. However, according to the present invention, such problems can be effectively avoided by the provision of the detecting section detecting any recording medium pending or unsettled between the carrier unit and the storage section or the drive unit and by the positional initialization control to automatically position the pending recording medium in the predetermined place of the carrier unit.
According to the present invention, each recording medium may be feed-transferred by the medium transfer mechanism and transported by the carrier unit, along with a predetermined tray-like mount or base supporting thereon the recording medium. By so doing, the present invention can be implemented as a DVD library apparatus. Namely, where each recording medium is disk-shaped like a DVD or CD medium and can not be directly engaged by the locking member for the transfer purpose, such a recording medium is supported on a separate tray-like mount or base (carrying tray) and transported along with the mount; in this case, the locking member engages the mount, rather than the recording member itself. Alternatively, the mount may be in the form of a cartridge or the like.